The present invention generally relates to intravascular drug delivery catheters. More specifically, the present invention relates to intravascular drug delivery catheters having a balloon with infusion holes for the delivery of a fluid drug therethrough.
A wide variety of intravascular drug delivery balloon catheters have been proposed for the treatment of vascular disease. An example of an intravascular balloon drug delivery catheter is disclosed in the U.S. Pat. No. 5,087,244 to Wolinsky et al. Wolinsky et al. disclose an over-the-wire type balloon catheter including a thin-walled flexible balloon having a plurality of minute holes through which medication may flow at a relatively low flow rate. Wolinsky et al. state that the balloon may be formed from various polymeric materials and preferably has a thin, flexible, inelastic wall.
In the treatment of certain types of vascular disease, particularly those involving soft occlusive material, vasospasms, and aneurysms, the provision of a drug delivery balloon having an inelastic wall is undesirable. For example, in the treatment of ischemic stroke caused by the formation of a blood clot, the use of an inelastic balloon is not optimal because the balloon does not conform to the soft clot material and may cause accidental dislodgment thereof before medication is delivered. Accordingly, there is an unmet need for an improved drug delivery balloon catheter for the treatment of soft blood clots, vasospasms, aneurysms, and other vascular diseases involving soft tissues.
To address this unmet need, the present invention provides an intravascular drug delivery balloon catheter and method of use, wherein the catheter incorporates a highly compliant balloon having a plurality of infusion holes. The highly compliant balloon elastically expands at a low inflation pressure (e.g., less than 1.0 ATM), and preferably has a compliance of 2.0 mm/ATM or more at pressures less than 2.0 ATM. A pressure relief valve that vents at pressures above a threshold pressure (e.g., 1.5 ATM) may be incorporated into the catheter to avoid over pressurization of the balloon that may otherwise cause over expansion of the balloon and/or over infusion of the drug. In one embodiment, the infusion holes are open when the balloon is deflated and enlarge when the balloon is inflated. In another embodiment, the balloon defines two inflatable lobes and the infusion holes are disposed between the lobes. The catheter may also include a guidewire seal to accommodate a single lumen design.